A parking assistance device is applied to a vehicle equipped with a camera for capturing an image of an area in front of the vehicle and is configured to assist forward parking of the vehicle in a parking space. The parking assistance device includes: a position estimation unit which, in a situation where the vehicle is advancing toward the parking space in a lateral passage of the parking space, estimates, based on an image captured by the camera, at least one of a first corner position, which is a near-side corner position at a vehicle entrance part of the parking space, and a second corner position, which is a far-side corner position at the vehicle entrance part, before the vehicle passes by the parking space; and a space recognition unit which recognizes the parking space for forward parking based on the at least one estimated corner position.